The present invention relates to a buckle device for an infant restraining seat, more particularly, to a buckle, used in a seat belt device of an infant restraining seat, which provides secure latching with a pair of tongues only when the both tongues are inserted therein simultaneously.
For safely securing an occupant when a vehicle comes into collision, various kinds of safety devices have been developed. A seat belt device is one of such safety devices. A seat belt device mounted inside a vehicle is generally designed to fit the length of a webbing thereof and its mounting position for an adult body similarly to a size of a seat. Hence, infant restraining seats are developed as means for effectively securing a child, particularly an infant.
In a typical infant restraining seat, movement of an infant sitting in a seat is restrained by an infant seat belt device. According to the infant restraining seat, the infant is restrained by softly holding the chest of the infant with a pad as a chest protector and a buckle with a large area. In addition, the infant is restrained by two shoulder belts holding areas from the both shoulders to the chest of the infant. The lower end of the buckle is fixed to a seat base by a crotch belt, the width of which is relatively large. The crotch belt restricts the buttocks of the infant from moving forward.
As for an infant seat belt device of this kind, for putting the seat belt to an infant, it is preferable that tongues of the shoulder belts are quickly connected to a buckle when the infant is seated.
However, even when tongue plates of the tongues are inserted into the tongue through holes, the tongues can not be latched sometimes when either of the tongues is insufficiently inserted or an object enters inside the buckle device. Therefore, there is a possibility that the tongues and the buckle are remained in a state in which engaging holes of the tongue plates and latch members are incompletely engaged (hereinafter, referred to as "the false latched state").
Each tongue is mounted to an end of each of the two shoulder belts. Therefore, it is necessary that the tongues are latched only when a pair of tongues are inserted to the buckle completely.
A buckle device for an infant restricting seat which solved such a problem is disclosed in U.S. Pat. No. 5,142,748 (hereinafter, referred to as "the conventional buckle").
FIGS. 1(a) and 1(b) are sectional views showing an operational state of an anti-false latching mechanism of the conventional buckle.
As shown in FIG. 1(a), a latch plate 101 which is formed in an oblong shape and is pivotally supported by a spring (not shown) is accommodated in a cover of the buckle 100. The latch plate 101 is provided with two wedge-shaped latch pawls 102 protruding from the surface thereof. When tongue plates 103 are inserted into tongue through holes 104 of the buckle 100, the latch pawls 102 engage engaging holes 105 of the tongue plates 103 to prevent the tongues from coming off. In the initial state, the latch plate 101 is urged by the biasing force of the aforementioned spring to latch the tongue plates.
Two ejectors 106 supported by ejector springs 107 are accommodated in the buckle 100. Ends 103a of the tongue plates 103 come in contact with the ejectors 106 when the tongue plates 103 are inserted into the buckle. The ejectors 106 have concave, arc-like portions 106a, respectively, so as to fit with the shape of the ends 103. As the ends 103a of the tongue plates 103 come in contact with the arc-like portions 106a and push the ejectors 106, the ejectors 106 are shoved to slide rearwardly against the biasing force of ejector springs 107.
The arc-like portions 106a are provided with elongated portions 106b at both ends thereof. The ends of the elongated portions 106b lie on the top of the latch plate 101, thereby preventing the latch plate 101 from pivoting to a position whereat the latch plate latches the tongues even though the latch plate 101 is urged by the biasing force of the latch spring (not shown).
In the initial state as shown in FIG. 1(a), as the tongue plates 103 are arranged and inserted into the tongue through holes 104, the two ejectors 106 are pushed by the ends 103a of the tongue plates 103 to move rearwardly simultaneously. Therefore, the latch plate 101 is released from the state in which the pivotal movement is prevented by the elongated portions 106b. As a result, the latch plate 101 pivots to the position whereat the latch plate latches the tongues so that the tongues are latched by the latch plate 101.
When one of the tongue plates 103 is inserted into the tongue through hole 104, only the corresponding ejector 106 is pushed to slide rearwardly (See FIG. 1(b)). Then, the holding of the latch plate 101 by the elongated portions 106b is released. However, the elongated portions 106b of the other ejector 106 corresponding to the tongue plate not inserted still prevents the pivotal movement of the latch plate 101. Therefore, the latch plate 101 does not pivot to the position whereat the latch plate latches the tongue plates 103. The buckle is not latched when only one of the tongue plates 103 is inserted into the tongue through hole 104 of the buckle.
However, in the conventional buckle, the elongated portions 106b of the ejectors 106 always restrict the pivotal movement of the latch plate 101 by holding the latch plate 101. Therefore, when the tongue plates 103 are inserted into the tongue through holes to push the ejectors 106 with the ends thereof, the tongue plates 103 are not smoothly inserted because the elongated portions 106b and the latch plate 101 rub together.
Also when releasing the tongues from the buckle, the tongues can not be smoothly ejected sometimes because the latch spring (not shown) pushes the latch plate 101.